I don't know what Predator fans are so worried about in regards to casting! You've got an A-list bonafide master director in Shane Black helming it. He's always gonna be the real coup. With him you're almost guaranteed a good movie. Just pray it gets to February and he's still on board.
He's the main ingredient, and the movie could be full of nobodies and it'd still be amazing. An A-lister though, for some of us, is just the very nice cherry on top.
Shane Black's inclusion is immensely validating for Predator fans, as he's an A-list filmmaker that sees the potential the franchise has AND is willing to step up to the plate to do something about it. Most Predator fans have been conditioned to thinking a Predator movie is MERELY a small, simple movie about 8 people getting knocked off one by one. That's not okay.
It'd just be nice if we had that sort of validation with A-list talent in FRONT of the camera, too. Downey Jr., Paltrow, Crowe, Gosling, all these people trusted Shane Black. It'd just be nice if that sort of caliber of person trusted him when it just so happens to be Predator Part Six.